1. Field of the Invention
This invention relates to a vehicle having multiple internal combustion engines whose power output can be combined and routed to a transmission for the purpose of improving fuel efficiency and accommodating the power needs of the vehicle.
2. Description of the Prior Art
Increasing greenhouse gas emissions to the atmosphere and the escalating cost of fossil fuels have spurred the search for means to improve automotive fuel efficiency. One solution has been the hybrid automobile which uses a small fuel-efficient internal combustion engine augmented by a battery-driven electric motor to power the vehicle. Another solution employs two or more internal combustion engines, using their combined power for acceleration, climbing steep grades, etc., and using the power of one engine to cruise economically.
The present invention relates to the latter solution, using two engines for acceleration, and one engine to cruise.
Prior dual engine systems have encountered difficulties involving the smooth and efficient interaction of the engines, and the routing of controlling amounts of fuel to the engines. For example, U.S. Pat. No. 4,421,217 to Vagias discloses a vehicle propulsion system involving a small engine employed to propel the vehicle economically in a cruising mode, and a large engine intended to add additional power when needed by the vehicle for acceleration, hill climbing or other power demands. In operation, the small engine, when in a situation where it is struggling to maintain propulsion of the vehicle, is automatically caused to start up the large engine. The start up procedure employs a clutch which unifies the crankshafts of both engines. Such procedure engenders stall-out of the small engine. Also, the integrated crank shafts are unlikely to produce a smooth combined effect because of differences in centrifugal balances and timing factors. Vagias' large engine cannot run independently because it must act through the small engine in order to transmit power to the transmission. This complicates the equitable supply of fuel to either the small engine alone or the integrated engines where both crankshafts rotate in unison.
Japanese Patent JP358026635A to Sakazaki discloses a vehicle having separate engines to drive the wheels of front and rear axles. Operator-manipulated individual accelerator pedals enable the operator to activate either or both engines. However, separate speed-change transmissions must be associated with each engine, thereby contributing to the cost and weight of the vehicle.
U.S. Pat. No. 6,637,283 to Belloso concerns a control apparatus for a continuously variable transmission, and is capable of accommodating two different power input sources. However, this is not commercially available, and said two power input sources must be received from opposite directions.
Accordingly, it is an object of this invention to provide a vehicle equipped with two engines for the purpose of achieving improved fuel efficiency through the use of a speed change transmission of commonplace design.
It is another object of the present invention to provide a vehicle of the aforesaid nature wherein the speed of each engine is separately controllable, and the output powers of said engines can be accumulated and fed to a speed change transmission.
It is another object of this invention to provide a vehicle of the aforesaid nature wherein the speed of each engine is controlled by adjustable supply of fuel to each engine.
These objects and other objects and advantages of the invention will be apparent from the following description.